It is quite often desirable to provide a feathered tip or feathered distal end zone on a relatively thin walled tube, such as a flexible catheter for injecting fluids intravenously into a patient. Such a tip should be smooth and gradually tapered. In the past this has been a difficult structure to produce. In the prior art it is known to grind the ends of plastic tube lengths to provide a taper or cut a taper on the end of such tubes. Because the same are thin walled this is a difficult, time-consuming and relatively expensive process. This invention is of an apparatus and process for forming a feathered tip on a plastic tube rendering it suitable for use as a medical catheter. It is also important that a plastic tube length, not only have a feathered tip but that the feathered tip closely conforms to a needle extending through and from the feathered end of the catheter so that when the needle jacketed by the catheter is inserted, flesh particles do not become trapped in the gap between the needle and the feathered catheter tip restricting movement of the catheter along with the needle to a point of positionment within a vein so that the needle can be withdrawn and the flow take place through the flexible relatively soft catheter. Also in the prior art, although it is known by various means other than that disclosed herein to taper the tips of such catheters for the purpose mentioned above, there is an additional problem. If the taper proceeds axially to a very thin feathered end, the end zone is relatively weak and hence susceptible to damage during insertion. Hence, it is preferred to provide a taper of the catheter tip zone in two stages, a proximal stage of tapering and a rather abrupt distal end zone taper so that the axial length of the thinnest portion is relatively short at the distal end. Finally, there is an additional problem and that is that after a tip has been processed according to prior art techniques it is important that the diameter of the tip zone be sized so as to snugly fit the needle so that a smooth insertion can take place of a needle jacketed by a catheter. It is believed that in the prior art it has been known to insert the end of a previously tapered tube into a heated die in an effort to form it by reducing the diameter to a proper configuration to mate with a needle to be used with it.
Further, it is believed that some in the prior art heat a die while engagedly the tip is being formed and retain it in engagement until the tube, tube tip and the forming die has been cooled by some type of cooling means.
The present invention is of an apparatus to rapidly and inexpensively make catheters with feathered tips as is described more fully hereinafter.